Software design of virtual forming technology of SMT solder joint
The first part is the SMT solder joint forming software. Its function is based on the principle of minimum energy in the solder joint system, using Surface Evolver fluid forming software, using finite element methods, and with the help of various established and stored initial models of solder joint shapes, according to the operator Various conditions input or selected in the form of man-machine dialogue will automatically carry out the shape evolution of the designed solder joints and output the resulting shape of the shape. The input is SMT solder joint design parameters, and the output is the corresponding solder joint shape graph or the coordinate value data file of each node on the outer surface of the solder joint shape.
The second part is the SMT solder joint shape reliability evaluation software. Its function is based on the stress-strain analysis and fatigue life calculation of the solder joint, and with the help of the accumulated and stored fatigue life data of various SMT solder joints, the specified solder joint shape Carry out stress analysis, life calculation and rationality evaluation, and output solder joint stress and strain, fatigue life value and morphological parameter revision suggestions. The input is the specific solder joint shape and structure parameters and material performance parameters (or parameter data file), and the output is the stress and strain distribution diagram of the solder joint and the fatigue life of the solder joint or the modification suggestion of the morphological parameter.
The solder joint shape evaluation methods are divided into manual analysis and evaluation methods and automatic analysis and evaluation methods. The former method analyzes and judges the thermal stress and strain analysis and thermal fatigue life calculation results of the solder joints before and after the secondary forming, and manually participates in the correction of the parameters to reshape and reanalyze the solder joints until a reasonable solder joint shape is obtained. The latter method uses stored empirical data or empirical formulas as the evaluation criteria to realize the automation of the analysis and evaluation process, integrate the SMT solder joint forming software and the solder joint thermal fatigue life reliability analysis and evaluation software, and enable the forming and The analysis process continues without interruption. In the automatic analysis and evaluation method, the empirical formula and data used as the basis for evaluation are a solder joint morphology analysis and evaluation expert system formed by using the former method to analyze and evaluate the accumulated experience and actual experience.
